OK..... How's this for a start? If others can use calipers to measure their Glocks (especially 21SF, 45gap. 45 and 10mm), we can develop a data base of real world dimensions. Perhaps I can repost the same image with the measurements for the other sized Glocks. Anyboby that disputes a measurement by a few hundreths can let me know and I'll average the numbers. I realize that some measurement may be subjuct to variation. My real goal here is to compare the 9,40,357 frame size to the 4, 45gap, 10mm and 21SF frames. In my town, it could be a year before we see a GAP or 21SF!! If there is support for this, I'll do rear frame view next.